Russia’s S-300 air-defense systems will be able to close Syrian airspace when necessary, Vladimir Ermakov, director of the Department for Non-Proliferation and Arms Control at the Russian Foreign Ministry, said on Tuesday. The arguments of Russia’s partners, who previously asked for the S-300s not to be delivered to Syria, have no effect anymore, RIA Novosti quoted him as saying. US National Security Advisor John Bolton said on Monday that the deliveries of S-300s to Syria would be a “significant escalation” by Moscow. Ermakov said that, in fact, such actions “will lead to the stabilization of the region, because we will be able to close the airspace where necessary, and, first of all, our servicemen who fulfill their international duty at the invitation of the Syrian government will be protected.” The S-300 systems “are purely defensive, so when the US says that defensive weapons are undermining its national security, it’s fudging,” the diplomat said.